1. Field of the Invention
This invention relates to an improved method and improved apparatus for rolling strip and, more specifically, relates to such methods and apparatus wherein undesired edge drop of the strip is resisted.
2. Description of the Prior Art
It is known that in the rolling of strips, the strip profile is impaired by the phenomena called "edge drop," which is primarily due to inherent bending of the ends of the rolls. This bending renders the strip more likely to have undesired "edge drop."
The "edge drop" or reduction in rolled material thickness in a lateral direction close to the edge, has proved troublesome. This defect is in part due to a combination of roll deflection and due in part to unrestrained edges of strip and the attenuated flattening of the work rolls at the strip-roll interface.
It has been known that "edge drop" can be decreased by shifting the rolls in a lateral direction in such a way that an additional deflection of the work rolls becomes possible near the edge of the strip. The problem with this approach is the need to provide sophisticated apparatus in order to accomplish both shifting and rotation of the rolls.
U.S. Pat. No. 4,059,976 discloses offsetting of work rolls in a downstream direction and the use of pressure compensating means to resist undesired work roll deflection.
U.S. Pat. No. 2,792,730 discloses the use of offset work rolls and a series of pressure controlled segmented rolls providing opposing forces. See also U.S. Pat. Nos. 1,964,504; 2,909,088 and 3,724,252.
In spite of the foregoing disclosures, there remains a real and substantial need for an effective means for resisting undesired edge drop.